The conventional reciprocating internal combustion engine produces power by converting heat energy to up-and-down mechanical energy of pistons which then is converted to rotational energy that drives the drive shaft. However, up and down piston movements induce unnecessary energy loss and unbalanced piston movements.
A currently commercially available rotary engine, i.e. the Wankel engine, is compact, light weight, simple in design, and capable of producing high torque output. However, it is not fuel efficient because of inherent engine design problems, such as the shape of the piston and piston housing.
Rotary engines which include a housing formed with a cylindrical shaped chamber in which one or more pairs of pistons are located are well known. Engines of this type are shown, for example, in U.S. Pat. Nos. 4,901,694--Sakita; 4,646,694--Fawcett; 3,398,643--Schudt; 3,396,632--Leblanc; 3,256,866--Bauer; and 2,804,059--Honjyo.
Problems with prior art rotary engines of the above-mentioned type include 1) the engine is not energy efficient because energy consumed by the following piston is excessively large, and 2) piston construction is complex, and sealing between pistons, and between pistons and the cylinder walls is difficult. A major cause of energy loss in such prior art rotary engines is due to dragging of the following, or trailing, piston in the angularly forward direction during the power, or expansion, phase of engine operation. This energy loss can be minimized by minimizing the amount of displacement of the following piston between the start and end of the power phase relative to the displacement of the leading piston. The sealing problem may be improved by adopting a different piston design.